Borate Cross-linking Research Articles

Adhesive and antibacterial guar gum-based nanocomposite hydrogel for remodeling wound healing microenvironment.

Hydrogels are promising wound dressings due to their extracellular matrix-like properties and tunable structure-function characteristics. Besides the physical isolation effect, hydrogel dressings are highly expected to possess tissue-adhesive performance and antibacterial capacity, which are beneficial for their clinical translations. Herein, a guar gum (GG)-based nanocomposite hydrogel was fabricated by mixing methacrylated GG (GGMA), acrylic acid, acrylated 3-aminophenylboronic acid, mangiferin (MF)-loaded cetyltrimethyl ammonium chloride (CTAC) micelles (MF@CTAC) and radical initiator. This hydrogel exhibited stable and tunable mechanical property as well as excellent biocompatibility. Borate crosslinking and physical interactions of the hydrogel produced a certain degree of self-healing ability, good tissue adhesive and hemostatic capacity. MF endowed the hydrogel with good antioxidant ability and excellent synergistic antibacterial ability with CATC. In vivo experiments indicated that the hydrogel significantly accelerated wound healing with a narrower wound edge, thicker granulation tissue, maturer epidermis and dermis tissue, higher collagen deposition level, milder inflammatory response, and enhanced angiogenesis. The hydrogel without adding antibiotics and other exogenous active ingredients showed great application potential as a versatile wound dressing material.

Evaluation of rheological properties of guar gum-based fracturing fluids enhanced with hydroxyl group bearing thermodynamic hydrate inhibitors.

Naturally occurring gas clathrates are a significant methane resource-the primary component of natural gas, regarded as the cleanest hydrocarbon and a key feedstock for producing gray and blue hydrogen. Despite the global abundance of gas hydrate reserves, extraction via depressurization has yet to achieve commercially viable production rates. The primary limitation lies in the low permeability of hydrate-bearing sediments, where solid clathrates obstruct porous pathways, hindering dissociation and slowing gas recovery. Hydraulic fracturing has emerged as a promising technique to enhance conductivity, with initial studies indicating substantial increases in production rates when stimulation is applied. This study investigates the integration of thermodynamic hydrate inhibitors (THIs), such as methanol and polyethylene glycol 200 (PEG-200), into conventional polymer-based linear and crosslinked fracturing gels to improve performance. By targeting both rock and the embedded gas hydrates, these inhibitor integrated fracturing gels aim to facilitate faster fracture propagation and accelerate hydrate dissociation. The rheological performance of THI-integrated gels at varying concentrations is analysed, crucial for fracture formation, propagation, and proppant transport efficiency. Additionally, microscopic observations of additive interactions followed by fluid disintegration according to time are compared to evaluate residue formation and long-term integrity. Results indicate that methanol slightly increased the viscosity of linear gels at low concentrations and improved stability, reducing residue and slowing degradation, while higher concentrations required additional polymerizing agents to maintain performance. PEG-200 enhanced viscosity and stability in guar-based gels at low concentrations but caused shear-thinning at higher levels, limiting its suitability for high-viscosity operations. Crosslinked gels demonstrated superior proppant suspension and stability, generating less sediment-damaging residue compared to linear gels, with methanol further enhancing performance. Optimized integration of PEG-200 during borate crosslinking is critical, as higher concentrations risk premature gel degradation.

Enhancing electromechanical conversion and motion-monitoring application of pore-oriented cellulose nanocrystal/agarose aerogel modified with flexible heterojunction structures

Oriented-porous cellulose nanocrystal (CNC)-based aerogels excel in directional energy conversion but face reduced toughness, and triboelectric performance bottlenecks owing to the absence of electron acceptors. In this work, we crosslinked quaternary ammonium CNC with another flexible carboxymethyl agarose (AG-), via borate dynamic bonds, exploiting the electron-accepting traits of boron and electrophilic modifications to boost the mechanical and triboelectric performance of aerogels. These results demonstrate that the compressive resilience and modulus of CNC/AG aerogel are improved up to 70.79 % (after 10-cycle 20 % strain) and 18.77 kPa attributing to the borate cross-linking network and oriented structure. Furthermore, the electromechanical response sensitivity and output energy density of the CNC/AG aerogel increased by 6.06 times (to 7.51 V/Hz) and 28.3 times (to 1.87 W/m2), respectively. The structure characteristics of the CNC/AG aerogel reveal that the oriented structure and heterojunction of the CNC/AG aerogel with electron transfer pathways reduce dielectric losses. The COMSOL simulation also show that oriented pores increase the polarization and charge density of the CNC/AG aerogel, thereby improving the electromechanical conversion efficiency. This work offers a synergistic approach for toughening aerogels and generating heterojunctions via flexible modification, presenting significant potential for smart devices with energy-collection ability.

Putative rhamnogalacturonan-II glycosyltransferase identified through callus gene editing which bypasses embryo lethality.

Rhamnogalacturonan II (RG-II) is a structurally complex and conserved domain of the pectin present in the primary cell walls of vascular plants. Borate cross-linking of RG-II is required for plants to grow and develop normally. Mutations that alter RG-II structure also affect cross-linking and are lethal or severely impair growth. Thus, few genes involved in RG-II synthesis have been identified. Here, we developed a method to generate viable loss-of-function Arabidopsis (Arabidopsis thaliana) mutants in callus tissue via CRISPR/Cas9-mediated gene editing. We combined this with a candidate gene approach to characterize the male gametophyte defective 2 (MGP2) gene that encodes a putative family GT29 glycosyltransferase. Plants homozygous for this mutation do not survive. We showed that in the callus mutant cell walls, RG-II does not cross-link normally because it lacks 3-deoxy-D-manno-octulosonic acid (Kdo) and thus cannot form the α-L-Rhap-(1→5)-α-D-kdop-(1→sidechain). We suggest that MGP2 encodes an inverting RG-II CMP-β-Kdo transferase (RCKT1). Our discovery provides further insight into the role of sidechains in RG-II dimerization. Our method also provides a viable strategy for further identifying proteins involved in the biosynthesis of RG-II.

A gel-based electrochromic device towards fast response and high coloration efficiency for low-power consumption smart window applications

Immobilization of viologen derivatives in the solid electrolyte can improve significantly the electrochromic performance and stability of a viologen-based electrochromic device (ECD). Here, we successfully developed a bis(3-hydroxyethyl) viologen dibromide-immobilized PVA/CMC/Borax gel-based ECD with high coloration efficiency, fast response, and long optical memory through an easy immobilization strategy. The bis(3-hydroxyethyl) viologen dibromide was immobilized in a borax-crosslinked polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC/Borax) gel electrolyte. With borate crosslinking, PVA and CMC existed in an interpenetrating polymer network (IPN), which lowers the crystallinity and glass transition temperatures of each polymer. This increase in mobility of ions through gel electrolyte leads to fast response and high coloration of ECD. The ECD exhibited fast response and high contrast ratio with a maximum contrast ratio of 98% with applying −2.5 V for a very short time of 10 s. The ECD showed a high coloration efficiency of 1280 cm2 C−1 at a switching voltage of −2.5 V, which is a high coloration efficiency value for viologen-based ECD reported so far.

Tuning the oxidation level of GO to construct high performance crosslinked lamellar graphene oxide membrane for pervaporation desalination

Lamellar graphene oxide (GO) membranes have received significant attention in desalination and water treatment due to their unimpeded permeation of water. Intercalation cross-linking is an effective way of improving the stability and perm-selectivity of GO membranes. This work reports a novel strategy to tune the nanostructure and morphology of GO membrane by combining highly oxidized GO nanosheets with borate cross-linking for desalination by pervaporation. The cross-linking processes covalent bonding of hydroxyl groups of GO membrane with sodium borate as the cross-linker, leading to formation of selective and stable three-dimensional GO-borate framework. The enrichment of hydroxyl groups on GO arising from high oxidation benefits the targeted cross-linking. Meanwhile, higher oxidation level of GO leads to higher content of carboxyl groups and improves the hydrophilicity of membrane. Consequently, the borate cross-linked GO membrane fabricated with fully oxidized GO simultaneously exhibits high water flux and enhanced structural stability. The results reveal that the interlayer spacing and swelling behavior of GO membranes are heavily influenced by the oxidation level and cross-linking, which are critical factors affecting the performance of the membranes in pervaporation desalination applications. The findings hold promise for the development of high-performance and stable GO membranes to address global water scarcity challenges.

Impacts of the hydroxyls crosslinking on lignin softening and pyrolysis via in situ 1H NMR, rheology, DRIFT and SPI-MS

The softening and foaming of lignin during pyrolysis are the main obstacles to the scale-up of lignin pyrolysis systems. In this study, the mechanism of borate crosslinking on lignin softening and pyrolysis process was investigated by combining in-situ physical and chemical techniques. First, the mobile protons and visco-elastic modulus during lignin pyrolysis were quantitatively analyzed by in-situ high temperature 1H NMR and rheology. It was found that the maximum content of mobile protons during the pyrolysis of raw lignin is around 90%. Hydroxyl crosslinking greatly inhibits the formation of mobile protons. The raw lignin produces a soft material from about 150 °C and starts to form a more rigid material from 200 °C. At 210 °C ~ 330 °C, mobile liquid-like intermediates are entrapped in the rigid char, forming “cavities”. With the addition of boron, the viscoelasticity tends to be stable and mainly elastic. Then, in-situ diffuse reflectance infrared Fourier transform spectroscopy and single photoionization time-of-flight mass spectrometry were used to characterize the evolution of functional groups and volatiles. It was found that the shielding of hydroxyl groups by borate inhibits the decomposition of lignin but improves the selectivity to phenols, and more oxygenated groups remain in the char.

Fabrication of stable MWCNT bucky paper for solar-driven interfacial evaporation by coupling γ-ray irradiation with borate crosslinking

Fabrication of stable MWCNT bucky paper for solar-driven interfacial evaporation by coupling γ-ray irradiation with borate crosslinking

Fundamentals of Capillary Electrophoretic Migration and Separation of SDS Proteins in Borate Cross-Linked Dextran Gels.

Recent progress in the development and production of new, innovative protein therapeutics require rapid and adjustable high-resolution bioseparation techniques. Sodium dodecyl sulfate capillary gel electrophoresis (SDS-CGE) using a borate (B) cross-linked dextran (D) separation matrix is widely employed today for rapid consistency analysis of therapeutic proteins in manufacturing and release testing. Transient borate cross-linking of the semirigid dextran polymer chains leads to a high-resolution separation gel for SDS-protein complexes. To understand the migration and separation basis of the D/B gel, the present work explores various gel formulations of dextran monomer (2, 5, 7.5, and 10%) and borate cross-linker (2 and 4%) concentrations. Ferguson plots were analyzed for a mixture of protein standards with molecular weights ranging from 20 to 225 kDa, and the resulting nonlinear concave curves pointed to nonclassical sieving behavior. While the 2% D/4% B gel resulted in the fastest analysis time, the 10% D/2% B gel was found to produce the greatest separation window, even higher than with the 10% D/4% B gel, due to a significant increase in the electroosmotic flow of the former composition in the direction opposite to SDS-protein complex migration. The study then focused on SDS-CGE separation of a therapeutic monoclonal antibody and its subunits. A combination of molecular weight and shape selectivity as well as, to a lesser extent, surface charge density differences (due to glycosylation on the heavy chain) influenced migration. Greater molecular weight selectivity occurred for the higher monomer concentration gels, while improved glycoselectivity was obtained using a more dilute gel, even as low as 2% D/2% B. This latter gel took advantage of the dextran-borate-glycoprotein complexation. The study revealed that by modulating the dextran (monomer) and borate (cross-linker) concentration ratios of the sieving matrix, one can optimize the separation for specific biopharmaceutical modalities with excellent column-to-column, run-to-run, and gel-to-gel migration time reproducibilities (<0.96% relative standard deviation (RSD)). The widely used 10% dextran/4% borate gel represents a good screening option, which can then be followed by a modified composition, optimized for a specific separation as necessary.

Golgi-localized membrane protein AtTMN1/EMP12 functions in the deposition of rhamnogalacturonan II and I for cell growth in Arabidopsis.

Appropriate pectin deposition in cell walls is important for cell growth in plants. Rhamnogalacturonan II (RG-II) is a portion of pectic polysaccharides; its borate crosslinking is essential for maintenance of pectic networks. However, the overall process of RG-II synthesis is not fully understood. To identify a novel factor for RG-II deposition or dimerization in cell walls, we screened Arabidopsis mutants with altered boron (B)-dependent growth. The mutants exhibited alleviated disorders of primary root and stem elongation, and fertility under low B, but reduced primary root lengths under sufficient B conditions. Altered primary root elongation was associated with cell elongation changes caused by loss of function in AtTMN1 (Transmembrane Nine 1)/EMP12, which encodes a Golgi-localized membrane protein of unknown function that is conserved among eukaryotes. Mutant leaf and root dry weights were lower than those of wild-type plants, regardless of B conditions. In cell walls, AtTMN1 mutations reduced concentrations of B, RG-II specific 2-keto-3-deoxy monosaccharides, and rhamnose largely derived from rhamnogalacturonan I (RG-I), suggesting reduced RG-II and RG-I. Together, our findings demonstrate that AtTMN1 is required for the deposition of RG-II and RG-I for cell growth and suggest that pectin modulates plant growth under low B conditions.

Regulation, Diversity and Evolution of Boron Transporters in Plants.

Boron (B) is an essential trace element in plants, and borate cross-linking of pectic polysaccharide rhamnogalacturonan-II (RG-II) in cell walls is required for normal cell growth. High concentrations of B are toxic to cells. Therefore, plants need to control B transport to respond to B conditions in the environment. Over the past two decades, genetic analyses of Arabidopsis thaliana have revealed that B transport is governed by two types of membrane transport molecules: NIPs (nodulin-26-like intrinsic proteins), which facilitate boric acid permeation, and BORs, which export borate from cells. In this article, we review recent findings on the (i) regulation at the cell level, (ii) diversity among plant species and (iii) evolution of these B transporters in plants. We first describe the systems regulating these B transporters at the cell level, focusing on the molecular mechanisms underlying the polar localization of proteins and B-dependent expression, as well as their physiological significance in A. thaliana. Then, we examine the presence of homologous genes and characterize the functions of NIPs and BORs in B homeostasis, in a wide range of plant species, including Brassica napus, Oryza sativa and Zea mays. Finally, we discuss the evolutionary aspects of NIPs and BORs as B transporters, and the possible relationship between the diversification of B transport and the occurrence of RG-II in plants. This review considers the sophisticated systems of B transport that are conserved among various plant species, which were established to meet mineral nutrient requirements.

Fire retardant cellulose aerogel with improved strength and hydrophobic surface by one‐pot method

AbstractBio‐based materials with multifunctional performance are getting immense attention nowadays for their environment friendly and renewable character. Inspired by toughening effect of graphene nanosheets and borate chemistry, a simple in‐situ borate crosslinking in water and freeze‐drying method was employed to fabricate a fire retarded bio‐based aerogel. The structure of the material was evaluated and analysis by SEM, XRD, FTIR, Raman and XPS. Importantly, the bio‐based aerogel has improved strength and adsorption properties due to unique structure. The compressive strength of rGO(reduced graphene oxide) + CMC (carboxymethyl cellulose) aerogel could reach 128 ± 2.1 kPa which is five times that of neat CMC aerogel. The bio‐based aerogel can load more than 2500 times of self‐weight. The adsorption capacity for organic solvents and oil of rGO+CMC aerogel is also greatly improved by a little rGO (1%) introducing due to its unique porous structure and hydrophobic nature of rGO. Additionally, rGO+CMC aerogel is also found fire resistant with relatively low thermal conductivity due to the borate and GO introduction.

Biomimetic galactomannan/bentonite/graphene oxide film with superior mechanical and fire retardant properties by borate cross-linking

With the great demand for high-strength integrated materials in various industries, products from renewable resources were expected to replace petroleum-based materials. Inspired by the hierarchical structure of nacre, in this work, bentonite and graphene oxide (GO) were incorporated into the galactomannan (GM) matrix to prepare a ternary nanocomposite, which was further cross-linked and strengthened with borate. The chemical structure of the composite was analyzed with SEM, FTIR, XPS and XRD, revealing a co-assembly reaction between GO, bentonite and GM, accompanied by the borate crosslinking. This synergistic strengthen effect resulted in a composite possessing a maximum tensile stress and toughness of 231.16 MPa and 4.53 MJ/m3, respectively, harder than most of the previously reported hemicellulose composites. Moreover, the nanocomposites showed excellent fire retardant property with a limiting oxygen index of 46.8 % due to the introduction of bentonite and GO, which shows potential application in fire-protective insulation, packaging and coating.

Borate crosslinking synthesis of structure tailored carbon-based bifunctional electrocatalysts directly from guar gum hydrogels for efficient overall water splitting

Given the efficiency, stability and sustainability, the carbon-based materials have become one of promising bifunctional electrocatalysts to the electrochemical water splitting, involving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, there are still many challenges about the design and mechanism study of the carbon-based electrocatalysts. In this paper, we reported B, N co-doping carbon nanosheets which were synthesized via cationic intercalation stripping guar gum carbon aerogels pre-crosslinked by borate, B(OH)4-. This facile strategy not only realizes the structure tailoring, but also concurrently improves the doping efficiency and the stability of the hetero atoms. Specifically, the cost-efficient carbon-based bifunctional catalyst (B5/GCS) shows an outstanding HER and OER performance displaying a remarkable activity both in acidic and alkaline media, low onset potentials for both HER (39.12 mV) and OER (1.38 V) in the same electrolyte (0.5 M H2SO4). Notably, when employed as the bifunctional electrocatalysts with a two-electrode electrolyzer for water splitting, the B5/GCS generated a cell voltage of 1.45 V to attain 10 mA cm−2 in 0.5 M H2SO4. Furthermore, a series of experiments combining density functional theory calculations revealed that the observed superb water splitting activity could be attributed to a synergistic effect of N, B co-doping and the formation of fragmented nanosheets with topological defects, which collaboratively promotes the proton adsorption and catalytic kinetics.

Bio-inspired lightweight pulp foams with improved mechanical property and flame retardancy via borate cross-linking

The ultra-lightweight and porous cellulose foam can be used in a broad range of applications (e.g. structural materials, sound insulation, thermal insulation), but the demands for high strength and fire-retardant properties are still challenges for the end uses. In this work, inspired by the cross-linking function of borate in plants, a lightweight and highly porous pulp foam with improved mechanical properties and flame retardancy was simply prepared via borate cross-linking. It was found that the prepared pulp foams had low density in the range of 13.3–16.4 mg/cm3, high porosity (>98%), and high compressional strength (up to 74.1 kPa, which was 28 times higher than that of pristine foam without borate). More interestingly, the pulp foam could be repeatedly squeezed more than 10 times without failure of its 3D structure. Compared with the readily flammable pristine pulp foam, the resultant pulp foams containing boron with low thermal conductivity (about 0.045 W/(m·K)) showed improved flame-retardant properties and excellent self-extinguishing behavior. When the content of boron was 3.45 wt%, the resultant pulp foam was completely incombustible. Therefore, this study provides a cost-effective and facile route for the fabrication of high-strength and porous pulp foams with excellent flame-resistance and heat insulation properties.

Bio-inspired layered nanolignocellulose/graphene-oxide composite with high mechanical strength due to borate cross-linking

Inspired by the borate cross-linking used by higher plants to strengthen their intercellular structure, high mechanical strength-layered composites based on borate cross-linked nanolignocellulose/graphene-oxide platelets were developed. Borate treatment and graphene deposition on nanolignocellulose surface were carried out by a mechanochemical method. The borate content is used in very low in these composites. The orderly layered structures produced by the flow-directed assembly of individual nanolignocellulose/graphene oxide platelets resulted in a synergistic toughening effect. The bending strength and elasticity modulus of the produced composites were ∼1.5 times higher than those of pure nanolignocellulose; they were also superior to those of lignin-based materials and comparable to those of medium density fiberboard (MDF) with resin. Such high-strength layered composites have potential as load-bearing materials in structural applications.

Borate crosslinking of polydopamine grafted carbon nanotubes membranes for protein separation

Poor dispersibility in aqueous media of polymer functionalized one-dimensional materials including carbon nanotubes (CNTs), inorganic nanoparticles and polymer nanofibers is an inherent challenge to their utilization in several applications. Herein, polydopamine grafted CNTs (PDA-CNTs) are rendered dispersible through chemical crosslinking via bioinspired borate chemistry. Nanolayer coatings of polydopamine are deposited on the side walls of CNTs forming aggregates that lead to highly dense and agglomerated PDA-CNTs sediments in aqueous media. Borate crosslinking facilitates the obtainment of a homogeneous dispersion of borate crosslinked PDA-CNTs (B-PDA-CNTs) by forming strong hydrogen bonds in solution and thus permitting the facile fabrication of B-PDA-CNTs membranes with an interconnected nanoporous structure on a macroporous support. The obtained membranes with a controllable thickness are stable and display good ultrafiltration performances of ferritin molecules (>90%) and high water permeability of more than 2.8 × 103 L m−2 h−1 bar−1. The borate chemical crosslinking highlights a versatile approach for the preparation of stable polydopamine coated nanomaterials for wide applications with bio-macromolecules and in nanocomposite materials.

Immunocytochemical detection of rhamnogalacturonan II on forming cell plates in cultured tobacco cells.

Rhamnogalacturonan II (RG-II) is a region of pectin macromolecules that is present in plant primary cell walls. The RG-II region serves as the site of borate cross-linking within pectin, via which pectin macromolecules link together to form a gel. In this study, we examined whether RG-II is present in the cell plate, the precursor of primary cell walls that forms during cytokinesis. A structure inside dividing cells was labeled with a rabbit polyclonal anti-RG-II antibody and detected by immunofluorescence microscopy. An antibody against callose, a marker polysaccharide for the cell plate, also labeled the structure. In immunoelectron microscopy analyses using the anti-RG-II antibody, gold particles were distributed in electron-lucent vesicular structures that appeared to correspond to the forming cell plates in late anaphase cells. Together, these results suggest that RG-II is present in cell plates from the early phase of their assembly.

Synthesis of borate cross-linked rhamnogalacturonan II.

In the present review, we describe current knowledge about synthesis of borate crosslinked rhamnogalacturonan II (RG-II) and it physiological roles. RG-II is a portion of pectic polysaccharide with high complexity, present in primary cell wall. It is composed of homogalacturonan backbone and four distinct side chains (A–D). Borate forms ester bonds with the apiosyl residues of side chain A of two RG-II monomers to generate borate dimerized RG-II, contributing for the formation of networks of pectic polysaccharides. In plant cell walls, more than 90% of RG-II are dimerized by borate under boron (B) sufficient conditions. Borate crosslinking of RG-II in primary cell walls, to our knowledge, is the only experimentally proven molecular function of B, an essential trace-element. Although abundance of RG-II and B is quite small in cell wall polysaccharides, increasing evidence supports that RG-II and its borate crosslinking are critical for plant growth and development. Significant advancement was made recently on the location and the mechanisms of RG-II synthesis and borate cross-linking. Molecular genetic studies have successfully identified key enzymes for RG-II synthesis and regulators including B transporters required for efficient formation of RG-II crosslinking and consequent normal plant growth. The present article focuses recent advances on (i) RG-II polysaccharide synthesis, (ii) occurrence of borate crosslinking and (iii) B transport for borate supply to RG-II. Molecular mechanisms underlying formation of borate RG-II crosslinking and the physiological impacts are discussed.

Borate cross-linking ratio of rhamnogalacturonan II as a diagnostic index of boron deficiency in broad bean grown in farmers&apos; fields

Borate cross-linking ratio of rhamnogalacturonan II as a diagnostic index of boron deficiency in broad bean grown in farmers&apos; fields